In recent years, the densities of storage elements and logical elements have been becoming higher through scaling. Integrated circuits have higher degrees of integration and higher capacities accordingly. This trend is conspicuous particularly among memory circuits.
However, it is predicted that, as long as the current fundamental structures of silicon (Si) memory devices are maintained, the scaling will soon reach its limit, and the increases in the memory chip density and capacity will stop.
To overcome the limit, an organic molecular memory that is a novel memory device using a single molecule or a molecular assembly as a memory element has been suggested, and test production of such organic molecular memories has been reported. As already reported, by using such organic molecular memories, a much higher density, a much higher degree of integration, and a much lower power consumption can be realized, compared with a case where conventional silicon devices are used.
In a memory element, a certain memory retention time is required. Therefore, the memory retention characteristics of the organic molecules used in memory elements need to be improved. Particularly, in a case where the use as a nonvolatile memory is intended, a long memory retention time is required, and therefore, further improvement of the memory retention characteristics is expected.